This invention relates to telescopes and binoculars, and more particularly pertains to a novel spotting system for such instruments which facilitates locating the target and which permits instantaneous shift to magnification of the target after it is located.
Binoculars are usually provided with magnifying capacities or power ranges of from 6.times. to lO.times. and at the latter magnifying power the field of view is fairly limited. Consequently, if one wants to locate a target, e.g., an airplane in the sky or a buoy at sea, it usually means sighting through the binocular and scanning the field of vision more or less randomly until the target is picked up. In some cases the approximate general location of the target can be ascertained with the naked eye; however, one is still faced with then having to locate the target through the binocular at the magnifying power. Since the field of view is limited, this can be a difficult task especially in those instances where the target is small or is moving.
A zoom lens arrangement could be employed. The lower power being used first to sight the target and the magnifying power thereafter increased as desired. To achieve the desired magnification takes time as the relative positions of the optical elements in the zoom lens arrangement are changed to effect magnification. During this time the target may have moved out of the field of view, necessitating relocation of the target. In addition zoom lenses, because of their relatively sophisticated and complex construction are expensive to manufacture, cannot stand up to rough handling and are susceptible to failure in severe or adverse use conditions. Further, such lenses are bulky and increase the weight as well as the cost of the binocular.
Accordingly, it is desirable to provide a spotting system for binoculars and telescopes which facilitates target location and which will permit instantaneous switching to the magnifying power once the target is spotted.